General microbiology

General microbiology
Copyright ©2021 Periowiki.com

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 Highlights in the history of microbiology
 Related terms
 Basic Classification
 Identification of microorganisms
 Bacteria
 Virus
 Mycology
 Parasites

 Composition of normal flora
 Immunoprophylaxis
 References

Microbiology :
 is the study of microscopic organisms, either unicellular (single cell),
multicellular (cell colony), or acellular (lacking cells).
 Covers several disciplines, including virology (study of viruses),
• bacteriology (study of bacteria), mycology (study of fungi), and parasitology
• (study of parasites). Each of these disciplines may include but is not limited to
• studies of infectious disease-causing microorganisms.
 Covers several disciplines, including virology (study of viruses),
bacteriology (study of bacteria), mycology (study of fungi), and parasitology
(study of parasites). Each of these disciplines may include but is not limited to
studies of infectious disease-causing microorganisms.

Historical introduction

early history of
microbiology
 Robert Hooke (1660’s)
. observed microorganisms
for the first time with a
microscope and coined
the term “cell”
Antonie Philips van
Leeuwenhoek (1632- 1723)
. Father of microbiology
. 1st microbiologist
. 1st to observe and describe
single-celled organisms
. Called microorganisms
“animacules”
theory of
spontaneous generation
Proposed by:
. Aristotle
. John Needham
(1745)
Opposed by:
. Lazzaro Spallanzani
(1768)
. Rudolf Virchow(1858)
. Louis Pasteur (middle to
late 1800s)

the germ theory
of disease
Louis Pasteur
(1822-95)
Robert Koch
(1843-1910)
the golden age
of microbiology
. many agents of different
infectious diseases were
identified.
. Many of the etiologic agents
of microbial disease were
discovered during that
period, leading to the ability
to halt epidemics by
interrupting the spread of
microorganisms.
1890’s
antibiotics were
introduced to
medicine
development of vaccines in
the 1950s and 1960s, such
viral diseases as polio,
measles, mumps, and
rubella came under control

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RELATED TERMS:
Microorganism: An organism that can be seen only with the aid of a microscope and
that typically consists of only a single cell
Habitat is an ecological or environmental area that is inhabited by a particular species
of animal, plant, or other type of organism
Niche is an area of a habitat providing conditions necessary for an organism or species
to survive.
Ecosystem is a community of living organisms (plants, animals and microbes) in
conjunction with the nonliving components of their environment (things like air, water
and mineral soil), interacting as a system
commensalism is a class of relationship between two organisms where one organism
benefits without affecting the other. It compares with mutualism, in which both
organisms benefit, amensalism, where one is harmed while the other is unaffected,
and parasitism, where one benefits while the other is harmed
opportunistic pathogen, an organism that exists harmlessly as part of the normal
human body environment and does not become a health threat until the body's
immune system fails.

Pathogen or infectious agent is a microorganism—in the widest sense, such as a virus,
bacterium, prion, or fungus—that causes disease in its host. The host may be an
animal, a plant, or even another microorganism.
Thermal death time is a concept used to determine how long it takes to kill a specific
bacteria at a specific temperature
Thermal death point is the temperature at which all organisms of a culture will be
killed by heat either instantaneously or within an arbitrary brief finite period
Vaccine is a preparation of a weakened or killed pathogen, such as a bacterium or
virus, or of a portion of the pathogen's structure that upon administration stimulates
antibody production or cellular immunity against the pathogen but is incapable of
causing severe infection
Immunoprophylaxis is prevention of illness by the introduction of active immunization
by vaccines or passive immunization through antisera.

Basic Classification

The hierarchy of biological classification
1. Superdomain system:
(Prokaryotes & Eukaryotes)
2. Three Domain system:
(Bacteria, Archaea, Eukarya)
(Archaea, Bacteria, Animalia, Plantae, Fungi, and Protista)

Eukaryotic Cell Prokaryotic Cell
Nucleus: Present Absent
Number of chromosomes: More than one One--but not true chromosome: Plasmids
Cell Type: Multicellular Unicellular
True Membrane bound Nucleus: Present Absent
Example: Animals and Plants Bacteria and Archaea
Telomeres: Present (Linear DNA) Circular DNA doesn't need telemeres
Genetic Recombination: Mitosis and fusion of gametes Partial, undirectional transfers DNA
Lysosomes and peroxisomes: Present Absent
Microtubules: Present Absent or rare
Endoplasmic reticulum: Present Absent
Mitochondria: Present Absent
Cytoskeleton: Present May be absent
DNA wrapping on proteins.: Yes No
Ribosomes: larger smaller
Vesicles: Present Present
Golgi apparatus: Present Absent
Mitosis: Yes No---but has binary fission
Chloroplasts: Present (in plants) Absent; chlorophyll scattered in the cytoplasm
Flagella:
Microscopic in size; membrane bound; usually
arranged as nine doublets surrounding two
singlets
Submicroscopic in size, composed of only one
fiber
Permeability of Nuclear Membrane: Selective not present
Plasma membrane with steriod: Yes Usually no
Cell wall: Only in plant cells (chemically simpler) Usually chemically complexed
Vacuoles: Present Present
Cell size: 10-100um 1-10um

Identificationof microorganisms

Morphological
characteristics:
(size, shape,
cellular
characteristics)
Differential
staining:
(gram & acid fast
staning)
Biochemical tests:
. Probe for specific enzyme
activities
. Rapid determination tools
(selective & differential
media, API test systems)
Serology
. Agglutination tests
. ELISA
. Western blot
Phage
typing/plaque
assay
DNA sequence methods
. DNA fingerprinting/
RELP analysis
. Polymerase chain
reaction
Nucleic acid
hybridization
. Southern blot
. DNA chips

Bacteria

INTRODUCTION:
. First forms of life to appear on Earth,
about 4 billion years ago.
. 17 March 2013, researchers reported
data that suggested bacterial life forms
thrive in the Mariana Trench, the
deepest spot on the Earth
. Once regarded as plants constituting the
class Schizomycetes, bacteria are now
classified as prokaryotes
. one particular group of bacteria, the
cyanobacteria or "blue-green algae,"
have left a fossil record that extends far
back into the Precambrian - the oldest
cyanobacteria-like fossils known are
nearly 3.5 billion years old, among the
oldest fossils currently known
Currently 30 phyla are accepted by LSPN

Basic features:
. Unicellular
. Lack nucleus,nucleolus,membrane-bound organelles & chlorophyll
. One-tenth the size of eukaryotic cells
. Typically 0.5–5.0 micrometres in length
. Do not show true branching, except in the higher bacteria (Actinomycetales)
. Ribosomes are smaller 70S type
. Some bacteria also transfer genetic material between cells. This can occur in three main
ways- transformation, transduction, bacterial conjugation, horizontal gene transfer . Gene
transfer is particularly important in antibiotic resistance as it allows the rapid transfer of
resistance genes between different pathogens. Copyright ©2021 Periowiki.com

. Bacteria grow to a fixed size and then
reproduce through binary fission. Under
optimal conditions, bacteria can grow and
divide extremely rapidly, and bacterial
populations can double as quickly as every
9.8 minutes
. 2 levels of bacterial growth:
increase in individual cell size and increase
in number of cells
. Growth in numbers can be studied by
by bacterial count:
total and viable count
. 4 phases of bacterial growth:
- Lag phase
- Exponential phase
- Stationary phase
- Phase of decline

Gram positive bacteria
Secretions:
. Essential for
bacterial survival
& adaptation
Gram Negative bacteria
(i) Listeria monocytogenes
(ii) Bacillus thuringiensis
(delta endotoxin)
Endotoxin:
. Mediate effects
through receptors
on monocytes,
Macrophages ,
dendritic cells (ii) Neisseria meningitidis
(i) lipopolysaccharide (LPS) or
lipooligosaccharide (LOS),
found in the outer membrane
of various
Gram-negative bacteria
Most well known virulence factors
(e.g. exotoxins of S aureus,
protective antigen of B anthracis,
listeriolysin O of L monocytogenes)
Escherichia coli peptide colicin V
Helicobacter pylori (CagA)
Yersinia pestis (LcrV)
Agrobacterium tumefaciens-
(VirB complex)
Exotoxin:
. Causes host cell lysis
. Destroyed by heat
. Active in minute
doses
S aureus & S pyogenes
(superantigens)
E. coli (heat-stable enterotoxins)
α toxin of C. perfringens
Listeria monocytogenes
(listeriolysin O)

Shapes: Spirochete
Spirilla
Vibrio
Actinomycetes
Cocci
Bacilli
Mycoplasma

Bacterial classification:
Gram
staining
Shape
Aerobic &
anaerobic
Motility
Spore &
non-
spore
forming
Antigenic
properties
Molecular
methods
(16s RNA
typing)

GRAM POSITIVE GRAM NEGATIVE
Rods Cocci
Aerobic/
facultative
anaerobic
Anaerobic
Aerobic/
facultative
anaerobic
(I) Non-sporing
(II) sporing
.Corynebacterium
. Listeria
. Nocardia
(I) Non-sporing
(II) sporing
. Bacillus . Clostridium
. Actinomyces
(I) Chains
. Streptococcus
(II) Clusters
. Staphylococcus
Cocci Rods Spirochete
Aerobes
. Nisseria
Anaerobes
. Leptospira
. Borrelia
. Treponema
Anaerobes
facultative
anaerobic
Aerobes
. Bacteroides
. Fusobacterium
. Acinetobacter
. P intermedia
. Pseudomonas
. Proteus
. Serratia
. Shigella (non-motile)
. Yersinia (non-motile)
. Brucella
. Pasteurella
. Bartonella
. Escherichia
. Klebsiella (non-motile)
. Haemophilus
. Enterobacter
. Bordatella
. Salmonella
. Campylobacter
(non-motile)
(motile)

Characteristic Gram positive Gram negative
Gram reaction
Retain crystal violet dye and stain dark violet
or purple
Can be decolorized to accept counterstain
(safranin); stain red
Peptidoglycan layer Thick (multilayered) Thin (single-layered)
Teichoic acids Present in many Absent
Periplasmic space Abesnt Present
Outer membrane Absent Present
Lipopolysaccharide (LPS) content Virtually none High
Lipid and lipoprotein content Low (acid-fast bacteria have lipids linked to
peptidoglycan)
High (due to presence of outer membrane)
Flagellar structure 2 rings in basal body 4 rings in basal body
Toxins produced Primarily exotoxin Primarily endotoxins
Resistance to physical disruption High Low
Inhibition by basic dyes High Low
Susceptibility to anionic detergents High Low
Resistance to sodium azide High Low
Resistance to drying High Low

Metabolism:
Nutritional
type
Source of
energy
Source of carbon Examples
Phototrophs Sunlight
Organic
compounds
(photoheterotroph
s) or carbon
fixation
(photoautotrophs)
Cyanobacteria,
Green sulfur
bacteria,
Chloroflexi, or
Purple bacteria
Lithotrophs
Inorganic
compounds
Organic
compounds
(lithoheterotrophs)
or carbon fixation
(lithoautotrophs)
Thermodesulfob
acteria,
Hydrogenophila
ceae, or
Nitrospirae
Organotrophs
Organic
compounds
Organic
compounds
(chemoheterotrop
hs) or carbon
fixation
(chemoautotrophs
)
Bacillus,
Clostridium or
Enterobacteriac
eae
cyanobacteria Green sulphur
bacteria
Clostridium
E. coli
Nitrobacter
T. indicus

Identification of bacteria:
1st stage tests:
( identify the genus of the
unknown bacteria)
1. Gram stain
2. Acid fast staining
3. Spores
4. Motility
5.Anerobic/anaerobic
growth
6.Catalase
7.Oxidase
8.Acid from glucose
9.Oxidative/Fermentation
reaction
2nd stagetests:
( identify the species of
the unknown bacteria)
1. Carbohydrate
fermentation
2. Hemolysis
3. Growth in the presence
of inhibitors like high salt,
bile
4. Species-specific tests
like coagulase for S aureus
3rdstagetests:
( used to further
differentiate closely
related species or
subspecies)
1. Antigenic
properties
Ex: LPS(O antigen)
and Flagella(H
antigen)

Modern methods:
Cyclic
amplification
techniques
Isothermal and
other
amplification
technologies
Detection of
bacterial pathogen
by multiple targets
or universal
targets
Detection of
bacterial
pathogens by
nucleic acid
hybridization or
mass
spectrometry

PCR, REAL TIME PCR, RT-PCR
permits the analysis of any short sequence of
DNA (or RNA) even in samples containing only
minute quantities of DNA or RNA. Previously,
amplification of DNA involved cloning the
segments of interest into vectors for expression
in bacteria, and took weeks. But now, with PCR
done in test tubes, it takes only a few hours.
NESTED PCR
detects 16S and 23S rRNA genes
from a variety of bacteria and provides multiple
overlapping amplicons for accurate sequencing
of these genes
PCR- ELISA
Yam et al. demonstrated, a biotinylated PCR-
ELISA for direct detection of M. tuberculosis
using a single-tube nested PCR method provides
a simple, accurate, high throughput test with
sensitivity and specificity comparable to the
commercial, PCR-based COBAS AMPLICOR
system (Roche Diagnostics) at around one-
fourth the cost
LIGASE CHAIN REACTION
Greater specificity than PCR, clinical advantages
over any other methods of diagnosing
gonorrhea and chlamydia
Cyclic amplification techniques

Isothermal & other amplification techniques:
Transcription-mediated amplification
Nucleic acid sequence-based amplification
Rolling circle amplification
Strand displacement amplificaiton
Cycling probe technology:
Branched DNA
Hybrid capture:

Detection of bacterial pathogens by
nucleic acid hybridization
or mass spectrometry
Fluorescence in situ hybridization
Peptide nucleic acid-FISH
Line probe assay
Hybridization protection assay
Mass spectrometry
Detection of bacterial pathogen by
multiple targets or universal targets
Sequencing
based
identification
Multiplex
PCR
Microarray


 Streptococcus species
 Neisseria
 Cornybacterium
 Pseudomonas
 Vibrio
 Staphylococcus spp
 Mycoplasma
 Actinomycetes
 Spirochetes
 Mycobacterium

Aggregatibacter actinomycetemcomitans
Aggregatibacter
Scientific classification
Domain: Bacteria
Phylum: "Proteobacteria"
Class: Gammaproteobacteria
Order: Pasteurellales
Family: Pasteurellaceae
Genus: Aggregatibacter
Type species
A. actinomycetemcomitans
• Small, short (0.4-1 microns), straight or curved
rod with rounded ends.
• It is facultative, indigenous, non-motile,
fastidious,non-spore forming, gram negative,
capnophilic, coccobacillus,commensal.
• Forms adherent and catalase-positive colonies
that have star-like centrally located structures.
• Causes periodontal disease, specifically localized
aggressive periodontitis, and a few other
extraoral infections, such as abscesses,
endocarditis and bacteremias
• They all decomposed hydrogen peroxide, were
oxidase negative and benzidine-positive,
reduced nitrate, produced strong alkaline and
acid phosphatases .
• Ferment fructose, glucose and mannose.
Variable
fermentation results were obtained with
dextrin,maltose, mannitol and xylose. Some
isolates produced small amounts of gas.
Hydrogen sulfide was not generated

Its role in periodontitis was
first discovered by Danish-
born periodontist Jorgen
Slots, currently a professor of
dentistry and microbiology at
University of Southern
California School of Dentistry.
An analysis of Actinobacillus
actinomycetemcomitans indicated
that it was monophyletic with
Haemophilus aphrophilus and
Haemophilus segnis, and it was
proposed that they be
reclassified as a new genus,
Aggregatibacter (from the Latin,
"aggregare", meaning "to come
together")
6 serotypes: (a-f), which are classified into 3
major phylogenetic lineages: (i) serotype b,
(ii) serotype c, and (iii) serotype a, d, e and f
described on the basis of differences in
polysaccharide composition.
- differences on the basis of geographic areas
have also been noted, for example: strains
from African patients have an increased
leukotoxin production. Multiple biotypes

SPECIAL PATHOGENIC CHARACTERISTICS: “ VIRULENCE FACTORS Aa ”
•LPS – endotoxin , Fatty acids are located in the lipid A moiety of lipopolysaccharide, which is
responsible for the toxicity of this macromolecule
•Leukotoxin- exotoxin plays a significant role in Aa pathogenicity
•Collagenase
•Protease
•Cytolethal distending toxin (Cdt)- exotoxin
•Immunosuppression factors that inhibit blastogenesis, antibody production and activate T-
suppressor cells
• Inhibition of PMNs functions
• Resistant to complement mediated killing
• Surface antigens
• Heat shock proteins
• Antimicrobial resistance
• Super antigens
Aggressive periodontitis

Culture Media for Aa:
Blood agar
AASM AASM
TSBV GCHB
DENTAID-1
Dentaid-1 : new medium, Dentaid-1, which
improves the detection of A.
actinomycetemcomitans in periodontal
samples. In its composition, blood and serum
have been omitted, hence reducing its cost
and making it a more restrictive medium
against the growth of other microorganisms
with high nutritional requirements. The
growth yields of pure cultures of the bacteria
on Dentaid-1 were comparable to those on
nonselective is a low-cost, noninhibitory
formula for the improved diagnosis and
monitoring of patients subgingivally infected
by this important oral putative pathogen.
blood agar

Porphyromonas gingivalis
Kingdom: Bacteria
Phylum: Bacteroidetes
Class: Bacteroidetes
Order: Bacteroidales
Family:
Porphyromon
adaceae
Genus:
Porphyromon
as
Species: P. gingivalis
Binomial name
non-motile,
gram-negative,
rod-shaped,
anaerobic pathogenic bacterium
It is found in the oral cavity, where it is
implicated in certain forms of periodontal
disease, as well as the upper gastrointestinal tract,
respiratory tract, and in the colon
P. gingivalis is divided into K-serotypes based upon
capsular antigenicity of the various types

Virulence factors Pg:
Gingipains: Arg-Gingipain (Rgp), Lys-
Gingipain (Kgp) are the gingipains secreted
by P. gingivalis
associated with coordinating the integrity of
the biofilm in the developing and maturation
phase
Capsular polysaccharide: when
present down regulates cytokine
production especially pro
inflammatory cytokines IL-1β, IL-6,
IL-8, and TNF-α indicating host
evasion responses
Fimbriae: characterized to be key
factors in adhesion, invasion, and
colonization.
3 types are:
Long: have a role in initial
attachment and organization of
biofilms. Short: cell-cell auto
aggregation , micro colony formation,
cell-cell adhesion with other dental
commensals, coadhere and develop
biofilm in conjunction with
Streptococcus gordonii.
Accesory: C,D, and E accessory
components associate with the main
FimA protein and have a role in
binding with matrix proteins and
interaction with CXC- chemokine
receptor 4.
Capsule: prevents phagocytosis
endotoxin, collagenase, phospholipase A,
hemolysin, fibrolysin, hemagglutins

Culture media Pg:
Porphyromonas gingivalis agar (P. GING)
appear opaque red
modified Wilkins-Chalgren (MWC) medium
Non-specific blood agar petridish
Appear brown, dark green or black
 Isolates seen are:
(JKG-I,7,9,33277
A7436,
D86B6, D13B11, D84D2, D67D9, D82F5)
WC broth was supplemented as follows:
500 mg/l cysteine hydrochloride; 250 mg/l
sodium thioglycolate; and 1,000 mg/l
sodium bicarbonate
OMIZ (Oral Microbiology and Immunology,
Zurich)-W1
 High concentrations of ascorbic
acid and ammonium ions proved to be
important for the growth
 Presence of hemin increased its
cohesiveness
 Protein or serum supplement required
for its growth

Tannerella forsythia
. Gram negative
. Obligate anaerobe
. Non-motile
. Highly pleomorphic rod
. Spindle-shaped
Belongs to the Cytophaga-Bacteroidetes family
Unlike other bacteria which synthesize their
own N-acetyl muramic acid, T. forsythia lacks
a metabolic pathway to synthesize its own
MurNac. This implies that T.
forsythia might possess unique systems to
scavenge peptidoglycan degradation products
released during cell-wall recycling of oral
biofilm bacteria.
succinate, produced by Tf
promotes the growth of Pg

Tanerella forsythia virulence factors
Protease and
apoptosis-inducing
activity
BspA (Bacteroides
surface protein A)
Leucine-rich repeat
cell-surface-
associated and
secreted protein
Sialidases SiaH and
NanH
Trypsin-like and
PrtH proteases
Alpha-D-
glucosidase and N-
acetyl-beta-
glucosaminidase
Methylglyoxal
production
S-layer
glycoproteins
Hemagglutinin

Culture media Tf:
Broth:
Tryptic soy
broth
Plate culture:
Agar media
N-acetylmuramic acid
(Important growth factor)
Present
regularly-shaped, short,
Gram-negative rods
Absent
retarded growth appear large,
filamentous and pleomorphic
with tapered (fusiform) ends

Treponema denticola
Treponema denticola
Domain: Bacteria
Phylum: Spirochaetes
Order: Spirochaetales
Family: Spirochaetaceae
Genus: Treponema
Species: T. denticola
• gram-negative
• obligate anaerobic
•motile
•highly proteolytic bacterium
T. denticola is related to the
syphilis-causing obligate
human pathogen,
Treponema pallidum subsp.
pallidum
T. denticolais also one of the only
spirochetes that has been
genetically mapped

Virulence factors of Treponema denticola:
leucine-rich repeat protein (LrrA)
Metabolic end-products (H2S, Methyl mercaptan
Toxin-antitoxin (TA) systems
Transposases
Outer sheath proteins
Dentilisin
Trypsin-like protease activity
Major sheath proteins Msp
Lipoproteins
Outer membrane vesicles
Motility & Chemotaxis
Periplasmic flagella

Culture
media for
Treponema
denticola
OMIZ (Oral
Microbiology and
Immunology,
Zurich)-W1
tryptone-yeast extract-
gelatin-volatile fatty
acids-serum (TYGVS)
medium
tryptone-yeast
extract-heart
infusion (TYH)
broth

Prevotella intermedia
Prevotella intermedia
Kingdom: Bacteria
Phylum: Bacteroidetes
Class: Bacteroidia
Order: Bacteroidales
Family: Prevotellaceae
Genus: Prevotella
Species: intermedia
Gram-negative ,rod shaped,non-spore forming, black
pigmented, obligate anaerobic pathogenic bacterium
Associated with :
. Necrotizing ulcerative gingivitis
. Chronic periodontitis
. Noma
steroids as growth factors, so their numbers are
higher in pregnant women
Prevotella intermedia 17 is the most common strain.
It is isolated from human periodontal pockets, and it
expresses type C (8-nm-diameter) ﬁmbriae
Virulence factors:
. Fimbrae . exopolysaccharides (EPS)
. interpain A proteinase
Culture media: . Non-specific blood agar (green
colonies) . Brucella broth & agar (Heamin-yeast-
menadione)

Campylobacter rectus:
Campylobacter rectus
Kingdom: Bacteria
Phylum: Proteobacteria
Class:
Epsilonproteobac
teria
Order:
Campylobacteral
es
Family:
Campylobacterac
eae
Genus: Campylobacter
Species: 'C. rectus'
Binomial name
Campylobacter rectus
Vandamme et al. 1991
Gram
negative
Facultative
anaerobe
Motile
(polar
flagellum )
short
rod
Virulence factors: flagellum, S-layer, cytotoxin
Belongs to the orange complex
Uptake of iron for survival and multiplication is
dependent on the ferric reductive pathway
Positve results for: oxidase, indoxyl acetate hydrolysis,
selenite & nitrate reduction.
Culture:
. in broth cultures growth is stimulated by formate &
fumarate
. Campylobacter-Wolinella Agar (CAMPY-WOL)
. Campylobacter rectus medium

Fusobacterium nucleatum
Fusobacterium nucleatum
Domain: Bacteria
Phylum: Fusobacteria
Order: Fusobacteriales
Family: Fusobacteriaceae
Genus: Fusobacterium
Species: F. nucleatum
. Non-spore forming
. Long tapered rods
Lectin & non-lectin
like in their affinities
generates capnophilic
environment essential for
the growth of P. gingivalis.
Blood agar CVE agar
Fusobacterium
selective agar
(FSA)
. Lemierre's syndrome( occasionally)
. Ventriculitis and brain abscess (rarely)

Streptococcus spp
Gram positive & divide in one plane
Spherical
grow in chains or pairs
Divided into obligate
(peptostreptococci) anaerobes &
facultative anaerobes
oxidase- and catalase-negative
Culture media:
. mitis-salivarius (MS) agar
. Strep select agar
. mitis salivarius bacitracin
agar (MSBA)
. blood agar plate (BAP)
. Azide Blood Agar with
crystal violet
Virulence factors:
S pyogenes: adhesins
S pneumoniae : capsule
Group A and B : C5a peptidase
Oral streptococci : GTF
Twenty-five species of oral streptococci
Five distinct species can be distinguished among
the oral streptococci S mutans, S sanguis, S
mitior, S milleri, and S salivarius

Ludwig’s angina:
Symptoms of Ludwig’s angina include:
1. Swelling of the submandibular and
sublingual areas
2. Pain on the tongue and neck
3. Redness and swelling of the neck
4. Fever
5. Malaise, weakness and fatigue
6. Dysphagia or difficulty in swallowing
Drooling
7. Difficulty breathing
8. Tachypnea (rapid respirations)
9. Stridor (a harsh sound heard during
inspiration which signals an obstructed
airway)
10. Confusion or mental changes due to
hypoxia
11. Earache as a sign of spread of the
disease to the ears
12. Unusual speech

Taxonomy of human oral streptococci
Group
Species Properties
Mitis
group
-S.mitis
-S.oralis
-S.sanguis
-S.parasangui
s
-S.gordonii
-S.peroris
-S.infantis
-S.australis
1) Pioneer species in plaque
formation
2) Common causative agents
of infectious
endocarditis
Mutans
group
-S.mutans
-S.sobrinus
1) Late colonizers of plaque
2) Increased numbers
associated with caries
Salivarius
group
-S.salivarius
-
S.vestibularis
1) Found on mucosal
surfaces
2) Rarely pathogenic
Anginosus
group
- S.anginosus
-
S.intermedius
-
S.constellatus
1) Favour anaerobic
environments
2) Frequently isolated from
abscesses
Recurrent streptococcal
pharyngitis

Neisseria spp
General features:
Gram negative(kidney-bean
appearance), aerobic, non-
sporulating, nonmotile,
part of the commensal flora of
mucosal membranes of humans
and some animals, and are
generally considered non-
pathogenic except for N.
gonorrhoea and N. meningitidis
thrive best at 98.6°F (37°C) in the
animal body or serum media.
catalase & oxidase positive
resemble coffee beans when
viewed microscopically
N. gonorrhoea N. meningitidis
Opa proteins, type IV pili LOS, fimbriae, capsule
Blood agar Chocolate agar
Causes: conjunctivitis,
pharyngitis, proctitis or
urethritis, prostatitis
and orchitis
Causes: Meningococcal
meningitis or septicaemia,
Waterhouse-Friderichsen
syndrome, adrenal
insufficiency, disseminated
intravascular coagulation
N.gonorrhoea N. meningitidis

Pseudomonas Mac Conkey
agar
ChromID
CPS agar
Colombia
blood agar
DCA MEDIA
Slender, gram negative,
motile by polar flagellum ,
non-sporing, piliated, non-
capsulated, strict aerobes
Grows well in ordinary media,
produces large opaque,
colonies, mawkish smell,
pigments(pyocyanin &
fluorescin)
Catalase, oxidase, aeginine,
dihydolase positive, nitrates
are reduced to nitrites &
further to gaseous nitrogen
Pathogenicity: Blue pus,
Nosocomial infections,
burns, Infantile diarrhoea
& sepsis
examples:
P. Aeruginosa group
P. chlororaphis group
P. fluorescens group
P. pertucinogena group
P. putida group
P. stutzeri group
P. syringae group
Seen to grow in
moist environment
 A few cause human infection,
typically opportunistic
P.aeruginosa

Corynebacterium
Slender rod, shows clubbing on one or both
the ends, pleomorphic, 3-6 microns – 0.6-0.8
microns, non-sporing, non-capsulated,
non-motile, show septa, gram positive,
polymetsphosphate granules, stained by
Loeffler’s methylene blue, aerobe a
facultative anaerobe. 3 strains: gravis, intermedius
& mitis, virulence: bacteriotoxin, corynephages,
iron concentration in the medium
Seen in pairs, palisades, at
various angles to eachother
resembling V or L called as
chinese letter or cunieform
arrangement
Ordinary media growth scanty,
optimum temp for growth 37
degree celcius,
- Loeffler’s serum slope
- Tellurite blood agar
- Mc leod’s and Hoyle’s media
C. diphtheria
Pathogenicity:
-Malignant or hypertoxic
- Septic
- Hemorrhagic
Other examples:
C. Ulcerans
C.Minutissimum
C.Tenuis
C.Pseudodiphtheriticum

Vibrio
Gram negative,
rigid, curved rods,
polar flagellum for
motility,
asporogenous,
noncapsulated
Present in
marine
environments &
surface waters
worldwide
V.cholerae- Koch
described it as “fish in
stream appearnace”,
strongly aerobic, temp(
37degree), growth:well in
alkaline medium, media:
blood agar, VR medium ,
Monsur’s taurocholate
tellurite, peptone water,
BSA
Pathogenicity: Cholera
Virulence: CT, TCP, LPS
Quorum sensing:
. 1st studied in
V.fischeri of type
(Luxl/R type)
. V.harveyi show
type hybrid
quorum sensing
V.fischeri
Photobacterium
sea water agar
V.cholerae

Staphylococcus species
1. Genus staphylococcus consists
of 40 species based on the
chemical composition of their cell
wall components
2. S.aureus, S.epidermidis,
S.haemolyticus, S.saprophyticus
can cause human diseases.
3. Staphylococci are perfectly
spherical cells about 1 micrometer
in diameter.
4. The staphylococci grow in clusters
because the cells divide
successively in three perpendicular
planes with the sister cells
remaining attached to one another
following each successive division
S.aureus : non-motile, non-sporing, grampositive,
non-capsulated, change to L forms under
the influence of penicillin
Cultural characteristics: 1.Ordinary media 2. Nutrient agar
3. Mc Conkey’s medium
Virulence factors: 1. Peptidoglycan 2. Teichoic acid
3. Capsular polysaccharide 4. Cell surface proteins
5. Clumping factor 6. Coagulase
7. Alpha, beta, gamma, delta, hemolysin
8. Enterotoxin 9. Epidermolytic toxin
Staphylococcal diseases: 1. skin & soft tissues
2. Musculoskeletal (osteomyelitis, arthritis, bursitis
3. Respiratory ( tonsillitis, pharyngitis, sinusitis,
empyema
4. CNS( meningitis, abscess, intracranial
thrombophlebitis
5. Endovascular(bacteremia, septicemia, pyemia,
endicarditis) Copyright ©2021 Periowiki.com

Mycoplasma
parasitic
Established
pathogen:
M.pneumoniae
Presumed
pathogen:
1. M. hominis
2. U. urealyticum
Non-pathogenic:
M. orale, M.buccale, M.
salivarium , M.faucium ,
M. fermentans, M.
spermatophilum
Saprophytic:
Acholeplasma
laidlawii
Lack cell wall,
highly pleomorphic
. Smallest free-living microorganisms
. Granular or filamentous forms
. Gram negative
. No spores, flagella or fimbria
. Facultative anaerobes
. Colonies have fried egg appearance
Pathogenicity :
2 types of disease:
1. Pneumonia
2. Genital infections
Labrotary diagnosis:
1. Isolation method
- throat swab or resp. secretion
& inoculation on mycoplasma
medium
2. Serological method
(i) Specific : using mycoplasmal
antigens
(ii) Non-specific:
- Streptococcus MG
- Agglutination tests

Actinomycetes
Cervicofacial actinomycosis
of greatest to the dentist
A.israelii
. Gram positive
. Non-motile
. Non-sporing
. Non-capsulated
True bacteria bearing superficial
resemblence to fungi
Actinomycetes of medical
importance
-Archinia, - Bifidobacterium
- Nocardia , - Dermatophilus,
- streptomyces

Diseases caused by Treponema
pallidum
Venereal syphilis T. palladium
pallidum
Endemic syphilis T. pallidum
endemicum
Yaws T. pallidum
pertenue
Pinta T.pallidum
carateum
Treponema pallidum
Spirochetes:

Treponema pallidum causes syphilis
Syphilitic chancre of the mouth:
. Primary syphilis
. Brownish, crusted appearance
. Reported at the site of fresh extraction
wound
Secondary syphilis:
. Oral lesions are called mucous patches
. Tongue, gingiva, buccal mucosa
. Serological reaction is always positive
Tertiary syphilis:
. Gumma
. Tongue, palate(perforation)
. Appears as firm, nodular mass which forms
deep painless ulcer

M
Y
C
O
B
A
C
T
E
R
I
U
M
Medical classification
M. tuberculosis complex tuberculosis
M. leprae Leprosy or Hensen’s
disease
Non- tuberculous
Mycobacteria (NTM)
pulmonary disease
resembling tuberculosis,
lymphadenitis, skin
disease, or disseminated
disease
M. leprae

H.Pylori and dentistry
Oral cavity as a reservoir of infection (i) patients with chronic gastritis
are with a higher prevalence of H. pylori in the dental plaque
than in the stomach. This shows that oral cavity may be the first place
for colonization and then the infection may involve the gastric
mucosa. Hence, the presence of H. pylori in the oral cavity could be
considered as main extragastric reservoir and possible source
of reinfection
(ii) The bacterium has been detected in saliva, supragingival
and subgingival plaque, suggesting that these sites may be
considered reservoirs for H. pylori not only in urease-positive
patients, but in healthy volunteers and thus be involved in the
reinfection of the stomach
H. pylori and oral health: Regarding oral health it has been
demonstrated that greater plaque index and a higher incidence
rate for gingivitis is observed in individuals with gastric H. pylori infection.
Some authors (Eskandari A., Mahmoudpour A., Abolfazli N., Lafzi A. 2010) have
found that H. pylori was scarce in patients
with periodontitis.
Oral manifestations and symptoms in patients with H. pylori infection: complain
of subjective symptoms such as month and tongue burning, numbness in the
mouth, altered taste, dry mouth, even in the absence of common typical
clinical symptoms of infection Copyright ©2021 Periowiki.com

Bacterial infection Oral manifestations
Scarlet fever(scarlatina)
caused by St.pyogenes
Soft palate- congested, petechie, fiery red
Tongue- white strawberry tongue and
raspberry tongue
Buccal mucosa- severe cases ulceration
Diphtheria
caused by Corny bacterium diphtheriae
Tonsils, tongue, lips, gingiva, buccla mucosa-
‘diptheritic membrane’
Soft palate- temporarily paralyzed
Larynx- edematous therefore husky voice
Submandibular & anterior cervial nodes-
enlarged and edematous, bull neck
appearance
Tuberculosis
Caused by Mycobacterium tuberculosis
Oral mucosa lesions are secondary to the
pulmonary disease.
Secondary lesions- Tongue mostly affected
Ulcer- irregular, sperficial or deep and painful
Primary lesions- involves gingiva(nodular or
papillary proliferation)
May involve bone of maxilla or mandible
Periapically- lesion is called tuberculoma
Bacterial infections and the oral cavity

Bacterial infection Oral manifestation
Tularemia caused by
Francisella tularensis
Oral mucosa and pharynx- necrotic ulcers,
painful
Submaxillary & cervical nodes- regional
lymphadenitis
Tetanus ( lock jaw)
Caused by Clostridium tetani
Facial muscles- risus scardonicus
Gonorrhea caused by Neisseria gonorrhea
Lips- acute painful ulceration
Gingiva- erythematious
Tongue, buccal mucosa, palate- red, dry
ulcerations
Pharyngititis, tonsilitis common
Granuloma inguinale
Causd by Calymmatobacterium granulomatis
Oral lesion classification: ulcerative,
exuberant., cicatrical (characteristic feature)
Lips, buccal mucosa or palate may be
involved
Noma caused by Vincent’s organisms Gingiva- begins 1st as small ulcer
Followed by sloughing out of the skin and
gangrene

VIRUS

General
properties
Do not
possess
cellular
organisation
Multiply by
complex
process
Ultramicros
-copic
Sensitive to
interferon
Lack
enzymes
Contain
either DNA
or RNA but
never both
Are obligate
intracellular
parasites
Poxvirus(300nm)- largest ;
Parvovirus(20nm)- smallest
Their shapes vary:
Animal viruses: roughly spherical
Bacterial viruses: complex morphology
They are stable at low temperatures and
are inactivated by sunlight, UV rays &
ionising radiations
A large no. have shown to agglutinate
erythrocytes from differnet species
2 stages of
viruses:
. Dormant phase
. Vegetative
phase
Viral assay:
. Total viral
particles
.infectious
virions only

Adsorption or
attachment
penetration
Uncoating
Biosynthesis
Maturation release
Viral multiplication

•A
 Is a virus that infects bacteria
 Phage T4 and phage lambda
both infect E.coli
Bacteriophage
Multiplication: 2 cycles:
 Lytic cycle and Lysogenic cycle
1) Attachment
2) Penetration
3) Biosynthesis
4) Maturation
5) Release
They are seen as a possible therapy against
multi-drug-resistant strains of many bacteria
(Front. Microbiol., 19 July 2012 Phage
therapy: concept to cure)
Felix d'Herelle(1873-1949) independently
discovered viruses of bacteria and coined the
term bacteriophage

Dmiti Iwanowski (1864-
1920) was the first person
to discriminate between
viruses and other infectious
agents. (TMV)
Martinus Beijerinick (1851-
1931) the person who
developed the concept of
the virus as a distinct entity
Freidrich Loeffler (1852-
1915) & Paul Frosch (1860-
1928) were the first to prove
that viruses could infect
animals as well as plants.
Walter Reed (1851-1902) his
coworkers were the first to
show that viruses could be
spread by insect vectors such as
mosquitoes . (Yellow fever)
H
I
S
T
O
R
Y
Karl Landsteiner (1868-1943) Erwin
Popper : proved that poliomyelitis
was caused by a virus. They were the
first to prove that viruses could
infect humans as well as animals
Frederick Twort (1877-1950) discovered
viruses infecting bacteria.

Viral genetics
The smallest viruses have only
a few genes; the largest
viruses have as many as 200.
Genetically, however, viruses
have many features in
common with cells.
Two main mechanisms for genetic
modification:
 mutation : . physical mutagens (UV light, Xrays)
. Natural behaviour of the bases of
nucleic acids
. fallibility of the enzymes that
replicate the nucleic acids
 Recombination: . Independent assortment
. Incomplete linkage

Virus
classification
International Committee
on Taxonomy of Viruses:
. six orders, 94 families,
22 subfamilies, 395
genera, and 2,480 species
of viruses have been
defined(2011)
. Consists of Order, family
subfamily,genus, species
Baltimore classification(1971):
(I) DNA virus: double stranded
single stranded
(II) RNA virus: double stranded
positive sense single stranded
negative sense single stranded
(III) Reverse transcribing virus:
single stranded RNA
double stranded DNA
Holmes classification (1948):
Group I: Phaginae (attacks bacteria)
Group II: Phytophaginae (attacks plants)
Group III: Zoophaginae (attacks animals)
LHT System (1962):
Phyla
Subphyla(DNA & RNA virus)
Class
order
family

Baltimore classification(1971):
(I) DNA virus: double stranded
single stranded
(II) RNA virus: double stranded
positive sense single stranded
negative sense single stranded
(III)Reverse transcribing virus:
single stranded RNA
double stranded DNA
Virus
classification

Virus family DNA examples
parvoviridae ss linear B 19
Papoviridae ds
circular
Papilloma
Polyoma
Adenoviridae ds
linear
Adeno
Hepadna
Viridae
ds
incomplet
e
Hepatitis B
Herpes ds
linear
HCMV,EBV
Hsv
Pox ds
linear
Small pox
vaccinia
DNA viruses
Picorna ss
linear
Polio, Rhino,
Hepatitis A
Reo ds
linear
Reo, Rota
Toga ss linear Rubella
Retro ss linear HIV, HTLV
Corona ss linear Corona
Calci ss RNA Norwalk agent
Orthomyx
o
ss linear Influenza
Paramyxo ss linear Measles, mumps
Rhabdo ss linear Rabies
Arena ss
circular
Lymphocytic
chorio meningitis
Bunya ss
circular
Sandfly fever virus
filo ss RNA Marburg, Ebola
RNA viruses

Laboratory diagnosis of viral infections
Direct Examination of Specimen
. Electron Microscopy morphology / immune
electron microscopy
. Light microscopy histological appearance –
e.g. inclusion bodies
. Antigen detection immunofluorescence,
ELISA etc.
. Molecular techniques for the direct
detection of viral genomes
Indirect Examination
1) Cell Culture - cytopathic effect,
haemadsorption, confirmation by
neutralization, interference,
immunofluorescence etc.
2) Eggs pocks on CAM - haemagglutination,
inclusion bodies
3) Animal inoculation
Classical Techniques Newer Techniques
1. Complement fixation tests
(CFT)
1. Radioimmunoassay (RIA)
2. Haemagglutination inhibition
tests
2. Enzyme linked immunosorbent assay
(EIA)
3. Immunofluorescence
techniques (IF)
3. Particle agglutination
4. Neutralization tests 4. Western Blot (WB)
5. Single Radial Haemolysis 5. Recombinant immunoblot assay
(RIBA), line immunoassay (Liatek) etc.
S
E
R
L
O
G
Y

Cultivation of virus
Animal inoculation
Embryonated eggs
tissue culture
Organ culture
Explant culture
Cell culture: primary, diploid
& continuous cell lines

Transmission of viral infections
Transmission
of viral
infections
Horizontal
transmission
1. Droplet contact
2. Fecal-oral
transmission
3. Sexual
transmission
4. Direct contact
Vertical
transmission

 Herpes viruses
 Hepatitis viruses
 Human immunodeficiency virus: HIV/AIDS
 Pox virus
 Myxoviruses
 Rhabdovirus

HERPES VIRUS
They are a species of
enveloped DNA
viruses that affect
humans and animals
The synthesis of viral
genomes and
assembly of capsids
occurs in the nucleus
Express enzymes for :
- Metabolism of nucleic
acids
- DNA synthesis
- Processing of proteins
Productive viral
infection is
accompanied by
inevitable cell
destruction
All herpesvirus
genomes contain
lengthy terminal
repeats both direct and
inverted. There are six
terminal repeat
arrangements
Characterized by
their ability to
establish latent
infections

Herpes simplex virus:
Type1:
lesions in and
around
mouth
Type2: genital
herpes
infections
Grow on cell
cultures:
monkey or
rabbit kidney,
human
amnion,
Herpes simplex HSV 1 :
1) Source of infection : saliva, skin lesions,
respiratory secretions
2) Transmission: direct contact or
droplet spread from cases or carriers
3) Symptoms: cutaneous - i) herpes fibrilis
ii) herpetic whitlow iii) Eczema herpeticum
mucosal – gingivostomatitis, pharyngitis,
herpes labialis
ophthalmic - acute keratoconjunctivitis
nervous system - bell’s palsy
Visceral- erythema multiforme, dyphagia
4 ) Lab diagnosis: Tzanck smear, ELISA

Varicella zoster virus:
VZV also fails to produce the LAT (latency-
associated transcripts) that play an important
role in establishing HSV latency (herpes
simplex virus).
VZV virons are spherical and 180–200 nm in
diameter. Their lipid envelope encloses the
100 nm nucleocapsid of 162 hexameric and
pentameric capsomeres arranged in an
icosahedral form. Its DNA is a single, linear,
double-stranded molecule, 125,000 nt long.
Vaccine: is a shot given subcutaneously
(under the skin). It is recommended for all
children under 13 and for everyone 13 or
older who has never had chickenpox. Two
doses are always recommended.
Chicken pox blisters
of mouth

Ebstein barr virus:
Oral manifestations:
1 )acute gingivitis
2) Stomatitis
3) Palatal pinpoint petechiae
4) Ocasional oral ulcers
5) Edema of the soft palate & uvula
Burkitt’s lymphoma:
1) Sporadic form : abdominal tumors
2) Ascites
3) Swelling of the jaw or other facial bones
4) Enlarged cervical lymph nodes
5) Histologically: starry sky appearance

cytomegalovirus
HCMV is among the most common causes of
oral diseases associated with AIDS patients
Active viral replication in the oral tissue
induces CMV-associated oral manifestations
such as ulcerations, aphthous stomatitis,
necrotizing gingivitis, and acute periodontal
infection
The presence of infectious particles in the oral
cavity including saliva is believed to be a
major source of HCMV horizontal
transmission
treatment with ganciclovir, which is effective
in treating HCMV infection in vivo , abolished
the growth of HCMV in cultured tissues

Herpes viruses and periodontal diseases:
1. EBV and HCMV were detected frequently in aggressive periodontitis sites. (Slots J.
Herpesviruses, the missing link between gingivitis and periodontitis? J Int Acad Periodontol 2004;6
(4): 113-119.)
2. HCMV can enhance the adherence of A.a to primary periodontal pocket epithelial
cells and to HeLa cells
3. The interaction between herpesviruses and bacteria is probably bidirectional, with
bacterial enzymes or other inflammation-inducing factors has the potential
to activate periodontal herpesviruses
4. EBV and HCMV infections up-regulate the interleukin-1beta and tumor necrosis
factor alpha gene expression of monocytes and macrophages. Increased levels of
proinflammatory cytokines in periodontal sites are associated with an enhanced risk of
periodontal tissue destruction
5.
Virus % of +ve samples in
aggressive
periodontitis
% of +ve samples in
chronic
periodontitis
Herpes simplex virus
(HSV-1) Imbronito et
al.
87% 40%
Epstein –Barr 29% 79%
HCMV 47% 50%

Human herpes virus 8 :
. It is a rhadinovirus
Kaposis sarcoma:
. Classic
. Endemic
. immunosuppression associated
. AIDS- related

Hepatitis virus
Hepatitis A Hepatitis B Hepatitis C Hepatitis Delta Hepatitis E
Virus family Picornavirus Hepadnavirus Flavivirus
Circular RNA similar
to plant viroid
Similar to Calicivirus
Nucleic acid RNA (+ sense)
DNA (partially double
strand)
RNA (+ sense) RNA (- sense) RNA (+ sense)
Disease caused Infectious hepatitis Serum hepatitis
Non-A, non-B
hepatitis
Enteric non-A, non-B
hepatitis
Size ~ 28nm ~40nm 30 - 60nm ~ 40nm 30 - 35 nm
Envelope No Yes Yes Yes No

Extrahepatic and oral manifestation
1) Hepatitis B and C viruses are present in whole saliva of infected humans
2) Jaundice is best visualized in the posterior palate, the floor of the mouth along the
lingual frenum and the buccal mucosa.
3) Although children under 2 years of age are often asymptomatic, hepatitis that results
in jaundice can result in yellow-green bile deposition of the dentin of developing
teeth
4) Viral-induced liver disease can cause intraoral bleeding, petechiae and ecchymoses.
5) The lichen planus associated with chronic HCV can be intraoral or extraoral and
appears in about 5 to 10% of patients with chronic HCV
6) autoimmune thyroiditis, rheumatoid arthritis, essential mixed cryoglobulinemia,
glomerulonephritis, Sjögren-like syndrome, keratoconjunctivitis sicca, lichen planus,
porphyria cutanea tarda, vasculitis, thrombocytopenic purpura.

Human immunodeficiency virus: HIV/AIDS
. Spherical
. 90-120nm in size
. Consists of 3 structural genes
(gag, pol and env)
. Also consists of non- structural
regulatory genes:
( tat, nef, vif, vpu, vpr, LTR)
. Major antigens: envelop, core,
shell and polymerase antigens
. Thermolabile

Oral manifestations
of HIV/AIDS
NUP
Linear gingival erythema
Oral hairy leukoplakia
Canker sores
Kaposis sarcoma
Angular cheilitis
Non- hodgkins
lymphoma
Pseudomembranous
candidiasis

LABORATORY DIAGNOSIS OF HIV INFECTION
(I) IMMUNOLOGICAL
TESTS:
(II) SPECIFIC TESTS
1) Antigen detection
2)Virus isolation
3) Polymerase chain reaction
4)Antibody detection:
- ELISA tests
- Western blot tests
Western blot test

Pox virus
Largest viruses that can
infect vertebrates & large
enough to be seen under
the microscope
Classified into 2
subfamilies:
- Chordopoxvirinae
- Entomopoxvirinae
Chordopoxvirinae classified into
6 genera :
1) Orthopoxvirus 2) Parapoxvirus
3)Capripoxvirus 4)Leporopoxvirus
5)Avipoxvirus 6)Suipoxvirus
Stable: if protected from sunlight & freeze dried
Antigenic stucture: NP, LS, heat labile L , heat stable S,
agglutinogen, hemagglutinin
On chick embryo:
(i) Variola pocks are : small, shiny, white, convex,
non-necrotic of which some are hemorrhagic
ceiling temp: 38 degree(major) and
37.5 degree(minor)
(ii) Vaccinia pocks are: large, irregular, flat, greyish,
necrotic lesions. Ceiling temp : 41 degree

Small pox:
General
manifestations
Oral
manifestations
1) Incubation period: 7-10days
2) Highfever, nausea, vomitting,
chills, heaadache
3) Severe pitting of the skin
is a common complication
Ulcers: oral
mucosa and
pharynx
Multiple
vesicles
Some cases,
tongue swollen
and painful

Clinical
features
• Elevated nodules
(5mm diameter)
• linear distribution
Oral
manifesta
tions
• lips, tongue,
buccal lesions
• not common
Histological
features:
• Henderson-Paterson
inclusion bodies
• 25 microns in
diameter
Molluscum Contagiosum

Picorna
virus
Picorna viruses are
non-enveloped,
positive-stranded
RNA viruses with an
icosahedral
capsid
17 genera:
Of medical
importance:
enterovirus &
rhinovirus
Unlike mammalian
mRNA picornaviruses
do not have a 5' cap
but a virally encoded
protein known as VPg.
However, like
mammalian mRNA,
the genome does have
a poly(A) tail at the 3'
end.
Picorna virus

Genera:
enteroviruses
Species:
(i) enterovirus: A-H, J
enterovirus A:
23 types of
coxsackie A virus
enterovirus B: 60
types coxsackie B
virus, & echovirus
enterovirus C:
23 type Polio
virus
Enteroviruses

Polio virus
Structure
Clinical features
Prophylaxis:
Oral polio vaccine (OPV):
3 doses at 4-8 week intervals
Injectable Polio vaccine (IPV) :
3 doses 4-6 weeks apart
Booster dose 6 months later
Laboratory diagnosis:
. Specimen isolation -
Blood, CSF, throat swabs,
feces

Coxsackie A virus
Examples:
1)mouth blisters (also known as
herpangina)
2) hemorrhagic conjunctivitis,
3)hand-foot-and-mouth disease,
4)aseptic meningitis
5)diseases of the upper
respiratory tract
Coxsackie A16 virus
Coxsackie A1, 6,8,10,
16,22 virus(herpangina)
Clinical features Oral manifestations
. Children & young
adults
. Sore throat
. Temp- 100-105
degree F
. Mild headache
. Anorexia
. Papules or nodules
surrounded by narrow
zone of erythema
. Appear on the uvula,
soft palate, anterior
pillars & posterior
oropharynnx
Acute lymphonodular pharyngitis

Myxovirus
paramuxovirus
1)Rubulavirus
. Mumps virus
2)Parainfluenzavirus
3)Morbillivirus
. Measles
4)Pneumovirus
. RSV
orthomyxovirus
Influenza virus

Mumps virus
Antigens:
S antigen &
V antigen
Virus isolated
from saliva,
CSF, urine &
inoculated into
chick embryos
Mumps (epidemic parotitis)
Differential diagnosis
. Sjogren syndrome
. Pleomorphic adenoma
. Parotid swellings due
(HIV, CMV etc)
. Non-specific mumps
. Nutritional mumps
. Chemical mumps
Prophylaxis:
. MMR vaccine

I
N
F
L
U
E
N
Z
A
V
I
R
U
S
Antigen Drift :
. Gradual change
. Point mutations in H&N
. Occurs in both A&B viruses
Antigenic shift:
. Occurs through gene ressortment
. Sudden change
. Explosive spread
. Occurs only in influenza A virus
3 forms: sporadic, epidemic, pandemic
Prophylaxis: Killed vaccines,
live vaccines
chemoprophylaxis

Measles:
Oral manifestations
. Koplik’s spot
. Histologically: Warthin
finkildey giant cells
MMR vaccine:
5ml
subcutaneous
ly 15-18
months
Laboratory diagnosis:
. Giemsa stained smears
of nasal secretions
. Serological diagnosis

Rhabdovirus:
. Bullet shaped, enveloped, single stranded RNA genome
. Classified as genera: (i) vesiculovirus (ii) lyssavirus
Genus: vesiculovirus
Consists of vascular
stomatitis virus
Genus: lyssavirus
Consists of rabies virus

Vescicular stomatitis virus
The genome of the virus is a
single molecule of negative-
sense RNA that encodes five
major proteins: G protein (G),
large protein(L),phosphoprotein,
matrix protein(M) and
nucleoprotein.
Humans can become
infected with VSV when
handling infected animals
(direct contact)
In affected people, vesicular
stomatitis causes a flu-like illness
with symptoms of fever, muscle
aches, headache and weakness.
Rarely, humans can get oral
blisters similar to cold sores.
Recovery usually occurs in four to
seven days
Use protective measures such as
gloves and a mask when handling
animals suspected of having
vesicular stomatitis. When
working with animals, good
personal hygiene with frequent
hand washing is important in
controlling most diseases that can
spread from animals to humans

Rabies virus
• glycoprotein
• nucleocapsid
antigen
Antigenic
properties
• Immuno-
fluorescence
• Isolation from :
brain, CSF, saliva
& urine
• PCR
Laboratory
diagnosis
• Neural
vaccines
• Cell culture
vaccine
• Passive
immunisation
Vaccination
schedules

MYCOLOGY

HISTORY
The term mycology and the complementary
mycologist were first used in 1836 by M.J.
Berkeley
start of the modern age of mycology begins
with Pier Antonio Micheli's 1729 publication
of Nova plantarum genera. Published in
Florence, this seminal work laid the
foundations for the systematic classification
of grasses, mosses and fungi

Cell
morphology
Yeasts:
. Cryptococcus
neoformans
Yeast-like:
. Candida albicans
Moulds:
. Dermatophytes
Dimorphic fungi:
. Fungi causing systemic
infections
Sexual
reproduction
phycomycetes
ascomycetes
basidomycetes
deuteromycetes
C
L
A
S
S
I
F
I
C
A
T
I
O
N

Individual hypha structure
Yeast cell
Morphology of fungus: 2 forms

Reproduction of fungi
Asexual:
. Spores produced by
mitosis
Sexual:
. Spores produced by
meiosis
Parasexual:
. Shows genetic
recombination without the
specific sexual structures

Superficial Deep opportunistic
Surface:
- Tinea versicolor
- Tinea nigra
- Tinea piedra
Cutaneous:
.dermatophytosis
. Candida albicans
Subcutaneous :
. Mycotic mycetoma
. Chromoblastomycosis
. Sporotrichosis
. Rhinosporidiosis
. Subcutaneous phycomycosis
Systemic mycosis:
.Cryptococcosis
. Blastomycosis
. Paradiococcidioidomycosis
. Coccidioidomycosis
. Histoplasmosis
1) Aspergillus
2) Penicillium
3) Mucor
4) Rhizopus
Classification based on nature of infection

Laboratory diagnosis of Mycoses
Different specimens include hair, skin scrapings, nail clippings, sputum, blood, CSF, urine,
corneal scraping, discharge or pus from lesions and biopsy
Microscopy
Culture
Serology
Antigen
detection
Skin tests
Molecular
Techniques:(DNA
hybridization, PCR)
• Sabouraud’s Dextrose Agar (SDA)
• Malt extract agar
• Potato dextrose agar
• Brain Heart Infusion Agar
• Inhibitory Mould Agar
• Caffeic Acid Agar and Birdseed Agar
• Corn Meal Agar
• Trichophyton Agars
• Dermatophyte Test Medium
• Sabhi Medium
• ‘CHROM agar Candida’
• Czapek-Dox medium

Candida albicans
Ovoid spherical
budding cell, produces
pseudomycelia, grows
rapidly at 25-37
degree centigrade
Relatively common
inhabitant
of oral cavity, GIT &
vagina.
2 forms:
Mucocutaneous
& systemic
Systemic form involves
chiefly the eyes, kidneys &
the skin
Mucocutaneous form
Involves:
Oralpharynx, esophagus,
Intestine, vulvovaginitis,
skin folds

Form of candidiasis clinical manifestations
1)Acute pseudomembranous
candidiasis
. More common form
. Plaques- soft, white, slightly elevated
. Buccal mucosa, tongue, palate, gingiva,
floor of the mouth
2) Acute atrophic candidiasis . Appear red & erythematous rather than white
. Only form which is consistently painful
. Occur at any site
3) Chronic hyperplastic candidiasis
(leukoplakia type candidiasis)
. Plaques- firm, white, persistent in nature
. Lips, tongue, cheek
4) Chronic localized
mucocutaneous candidiasis
. Severe form occuring early in life
. Typical white plaques in the oral cavity
. Skin(widespread involvement) scalp and face
shows granulomatious & horny massses, nails
also involved
5) Candidiasis endocrinopathy
syndrome
. Classic involvement of oral cavity with
either(Addison’s disease, DM, hypopara-
thyroidism, hypothyroidism)
. Common finding enamel hypoplasia
6) Chronic diffuse
mucocutaneous candidiasis
. Least common form, oral presentation similar
to chronic hyperplastic candidiasis
7) Chronic atrophic candidiasis . Denture bearing area with angular cheilitis

Other mycotic
infections of the oral
cavity
Clinical features Oral manifestation
Gilchrist’s disease
Caused by
Blastomyces
dermatitidis
. Middle aged men
. Crateriform lesions
typical
. Skin- small red papules
. Lungs- cough, other
symptoms typical of
pulmonary tuberculosis
. Tiny ulcers
. DD- epidermoid
carcinoma
Lutz’s disease
Caused by
Blastomyces
brasiliensis
. Organisms demonstrated in the periodontal
membrane & periapical granuloma are seen
to produce severe lympadenopathy
. After tooth extraction- produce papillary
lesions of the oral mucosa
. Widespread oral ulcers common finding
Histoplasmosis
caused by
Histoplasma
capsulatum
(DD- vincent’s
angina)
. Localized & generalized
forms
. Low-grade fever,spleno-
megaly, hepatomegaly,
lymph adenopathy,
productive cough
. Nodular, ulcerative
or vegetative
lesions
. Buccal mucosa,
gingiva, tongue,
palate & lips

Mycotic infection Clinical features Oral manifestations
Coccidioidomycosis
Caused by
Coccodiodes immitis
nondisseminated
form:
Respiratory disease
Disseminated form:
Spread from lungs to
viscera, bones, joints, skin
CNS
.Oral mucosa:
proliferative,
granulomatous,
ulcerated, marked
chronicity, healin by
scar, clinically non-
specific
. Jaws: lytic lesions
Cryptococcosis
Caused by
Cryptococcus
neoformans,Cryptoc
occus bacillispora
.middle-aged males
. Skin: ulcerating
multiple brown
papules
. Lungs: nonspecific
pneumonitis symptoms
. CNS: neurologic signs,
increased intracranial
pressure
. 1st evidence of
the disease
. Ulcers- simple,
non-specific,
single or mulltiple
Geotrichosis
Caused by
geotrichum species
. Lungs: Pneumonitis or
bronchitis symptoms
. Oral mucosa-
white,velvety,
isolated or diffuse
patchlike covering

Mycotic infection Clinical features Oral
manifectations
Phycomycosis
Caused by
rhizopus, mucor,
absidia
1. Superficial form:
. Involves external
ear, fingernails, skin
2. Visceral 3 forms:
(Pulmonary. Gastro-
intestinal, rhino-
cerebral)
. Maxillary sinus-
tissue sloughing,
sinus tracts,
necrosis, clinically
present as a mass
Sporotrichosis
Caused by
Sporotrichum
scheinckii
. Skin- sporotrichotic
‘chancres’(firm,red-
purple nodules)
. Also can involve- nasal,
phyrageal mucosa, sub-
cutaneous tissues
. Oral mucosa-
non-pecific
ulcers, heal with
soft,pliable scars,
regional lymph-
adenopathy
Rhinosporidiosis
Caused by
Rhinosporidium
seeberi
. Nasal mucosa- small
verrucae or warts, which
become pedunculated
. Oropharynx-soft,
red, polypoid
growth, vascular
. Soft palate: most
frequent site
. Parotid duct-
involvement
unusual

• The first written records of what
are almost certainly parasitic
infections come from a period
of Egyptian medicine
3000 to 400 BC
Thabes
• important medical works that
contain a great deal of
information about diseases
clearly caused by parasites
Rhazes (AD 850 to
923) (226) and
Avicenna (AD 980 to
1037)
• science of helminthology really took off.
• Linnaeus described and named six
helminth worms(Ascaris lumbricoides,
Ascaris vermicularis, Gordius
medinens,Fasciola hepatica, Taenia
solium, Taenia lata
17th to 18th
century
• first person to see protozoa, using
microscopes he constructed with simple
lenses. Between 1674 and 1716, he
described, in addition to free-living
protozoa, several parasitic species from
animals, and Giardia lamblia
Anton van
Leeuwenhoek
H
I
S
T
O
R
Y

Human parasites:
Classification
Unicellular
(Protozoa)
Multicellular
(Helminths &
arthropods)
Endoparasites
. Intestinal
. Atrial
. Body tissues
Ectoparasites
. Are arthropods
that cause
diseaes
. Act as vectors
transmitting
other parasites
Classified as 6 phyla
Most species causing
human disease are
members of the phyla:
1. Sacromastigophora
2. Apicomplexa.
1) Phyla Nemathelminthes:
-class: Nematoda(round worms)
2) Phyla Platyhelminthes:
-class: Cestoda(tapeworms)
- class: Trematoda(flukes)

Reproduction
1)Sexual : involves the
production of gametes
(In Plasmodium,
Toxoplasma, and
other apicomplexans)
2) Asexual :
-Binary fission
- endodyogeny
- schizogony
protozoa have life
stages alternating
between proliferative
stages (e.g.,
trophozoites) and
dormant cysts
PROTOZOA

Protozoa related to the oral cavity
T. tenax is regarded as a
harmless commensal of the
human mouth. This parasite
feeds by phagocytosis and
pinocytosis of food debris and
bacteria from the oral cavity
It is found in and around
diseased and necrotic
teeth and gums. Saliva is
the route of transmission
The active
participation of the
flagellate is seen in
oral inflammatory
disease has been
Lab diagnosis :
1. trophozoites in scrapings
of the gums and teeth
2.Samples:deep pockets,
saliva ,calculus, plaque
T
R
I
C
H
O
M
O
N
A
S
t
e
n
a
x
•fixated and stained :
1. Giemsa stain,
2. trichrome stain or
3. gram stain
4. Kupferberg Trichomonas
broth
•Reviewed and studied with:
1. scanning and transmission
electron microscope
2. serology
phylum: Protozoa,
sub-phylum:
Mastigophora
class:
Zoomastigophorea
Genus:
Trichomonas,
Species: T. tenax

Entamoeba gingivalis phylum: Protozoa,
sub-phylum:
Sarcodina, class:
Archamoebae.
Genus: Entamoeba,
Species: E. gingivalis
E. gingivalis is a non-
pathogenic parasitic protozoa
of the oral cavity, most often
found in gingival tissues
around teeth, gums and
tonsils
More common in
gingivitis but are
not the cause for
the same
Feed on epithelial cells of the
mouth, bacteria, food debris,
and other cells available to
them

HELMINTHS
NEMATODE
CESTODE
TREMATODE
Life-cycles
Helminths form three main
life-cycle stages: eggs, larvae
and adults.
Parasitological
tests
Serological
assays
Antigen
detection
tests
Molecular
diagnosis
other specific tools
for parasite
detection in
arthropod vectors
or snail (or other)
intermediate hosts.
Laboratory
Diagnosis

Ancylostomiasis
Elephantiasis
Enterobiasis results of
colonoscopy

Helminthic diseases that may manifest oral involvement include
Gongylonema nematode
species of Dipterous flies among the
genera Chrysomya and Cochliomyia
have been reported to be the most
important obligatory myiasis among
human and/or domestic animals
Unknown

Normal flora
BENEFICIAL EFFECTS HARMFUL EFFECTS
The normal flora synthesize and excrete vitamins:
in excess of their own needs, which can be
absorbed as nutrients by their host
Bacterial synergism between a member of the
normal flora and a potential pathogen
The normal flora prevent colonization by
pathogens by competing for attachment sites or for
essential nutrients. This is thought to be their most
important beneficial effect, which has been
demonstrated in the oral cavity, the intestine, the
skin, and the vaginal epithelium
Competition for nutrients contributes to the
development and spread of bacterial antibiotic
resistance within the farm animals, as well as
humans
The normal flora may antagonize other bacteria:
through the production of substances which inhibit
or kill nonindigenous species
Induction of a low grade toxemia
The normal flora stimulate the development of
certain tissues :
The normal flora may be agents of disease:the
normal flora may cause endogenous disease if they
reach a site or tissue where they cannot be
restricted or tolerated by the host defenses
The normal flora stimulate the production of
natural antibodies :Low levels of antibodies
produced against components of the normal flora
are known to cross react with certain related
pathogens, and thereby prevent infection or
invasion
Transfer to susceptible hosts :Some pathogens of
humans that are members of the normal flora may
also rely on their host for transfer to other
individuals where they can produce disease

Anatomical Location Predominant bacteria
Skin staphylococci and corynebacteria
Conjunctiva sparse, Gram-positive cocci and Gram-negative rods,
Staphylococcus epidermidis and certain coryneforms
(Propionibacterium)
Oral cavity streptococci, lactobacilli, staphylococci and
corynebacteria, with a great number of anaerobes,
especially bacteroides,
teeth streptococci, lactobacilli
mucous membranes streptococci and lactic acid bacteria
Upper respiratory tract Staphylococcus epidermidis and corynebacteria,
nares (nasal membranes) staphylococci and corynebacteria
pharynx (throat) streptococci, neisseria, Gram-negative rods and cocci
Lower respiratory tract none
Gastrointestinal tract Acid tolerant lactobacilli
stomach Helicobacter pylori (up to 50%)
small intestine lactics, enterics, enterococci, bifidobacteria
colon bacteroides, lactics, enterics, enterococci, clostridia,
methanogens
Urogenital tract
anterior urethra sparse, staphylococci, corynebacteria, enterics
vagina lactic acid bacteria during child-bearing years; otherwise

Sterilization and disinfection

Antiseptic agents used in periodontal therapy
Povidine iodine10%
solution in water, yielding
1% (10,000 ppm)
available iodine
Chlorhexidine
0.2% to 0.12%
Cetylpiridium chloride
0.045% to 0.1%
Triclosan
0.03%
Essential oils
Sodium hypochlorite
0.2%, 0.05%

Host – microbe interactions:

PERIODONTAL VACCINES
HISTORY: Early 20th century, 3 periodontal vaccines were
employed:
1. Pure cultures of streptococcus & other organisms
2. Autogenous vaccines
3. Stock vaccines
Ex: Vancott’s vaccine & Inava endocarp vaccine
Types of periodontal immunization:
Genetic immunization:
1. Plasmid vaccines
2. Live viral vector
vaccines
Passive immunization
1. Murine monoclonal
antibody
2. Plantibodies
Indications:
1. Severs periodontal disease
with bone loss around teeth
2. Excarebted DM and CVD
Limitations of periodontal vaccine:
• complexity of the periodontopathogens
• Incidence of toxic reactions to inactivated
whole cell vaccines
• Problems of maintaining adequate levels
of antibodies for long time
• Multiple antigenicities of various
micro-organisms
Active immunization
1. Whole bacterial
cells
2. Sub unit vaccines
3. Synthetic peptides
as antigens

References
1. Ananthanarayan and Paniker’s textbook of microbiology 7th edition
2. Shafer’s textbook of oral pathology 5th edition R rajendran B Sivapathasundharam
3. Classification of microorganism chapter 10 from Tortora G.J. Microbiology An Introduction
8th, 9th, 10th ed. San Francisco: Pearson Benjamin Cummings, 2004, 2007, 2010
4. Nucleic acid-based methods for the detection of bacterial pathogens: Present and future
considerations for the clinical laboratory Elizabeth A. Mothershed *, Anne M. Whitney
5. Fungal infections of the oral mucosa: Review article Anitha Krishnan P
International Journal of Dental Research, 23(5), 2012
6. History of human parasitology F.E.G. Cox clinial micrbiol . Rev. 2002, 15(4):595.
7. INTRODUCTION TO MEDICAL PARASITOLOGY Manar M.S. El-Tonsy
MEDICAL SCIENCES- introduction to medical parasitology

7. The Normal Bacterial Flora of Humans © Kenneth Todar, PhD
Online textbook of Bacteriology
8. The history of virology: Principles of molecular virolgy 3rd edition
9. Medical microbiology 4th edition:
. Chapter 77 Protozoa: Structure, Classification, Growth, and Development
. Chapter 86Helminths: Structure, Classification, Growth, and Development
Gilbert A. Castro. . Case Report:
10. Primary Oral Myiasis: A Case Report
Nitin Bhola, Anendd Jadhav, Rajiv Borle, Nitin Adwani, Gaurav Khemka,
and Pretti Jadhav Case Reports in Dentistry Received 22 August 2012; Accepted
29 September 2012
11. Periodontal vaccine: A dream or reality
Nitin Kudiyar, Nitin Dani, Swapna Mahale
Journal of Indian society of Periodontology- Vol 15, Issue 2, Apr-Jun 2011

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